Index: Which countries are perceived to be the most corrupt?

Transparency International ranks countries by their perceived levels of corruption

Somalia is perceived to be the most corrupt of the 178 countries, territories on the list

Denmark, New Zealand and Singapore are perceived to be the least corrupt

Editor's Note: Each Friday, CNN will examine statistics or world rankings to show how countries and territories compare with one another. Who's the best? Who's the worst? And where does the United States fit in? You'll find those answers in our Country Comparisons series.

(CNN) -- Somalia, Myanmar and Afghanistan have the lowest scores on Transparency International's Corruption Perceptions Index, which measures how people in 178 countries and territories view corruption in their public sectors.

On a scale of 0-10, with 10 being "very clean" and 0 being "highly corrupt," all three countries score below 1.5. Somalia is the lowest at 1.1, while Myanmar and Afghanistan are tied for second at 1.4.

At the other end of the list are Denmark, New Zealand and Singapore, which score the highest at 9.3.

The United States, with a score of 7.1, is among the countries viewed as least corrupt. It's tied for 22nd overall with Belgium. But while the U.S. is well ahead of neighbor Mexico (3.1), it seems to have some work to do to catch Canada (8.9).

Because of activist Anna Hazare, right, corruption has been brought to the forefront in India.

The latest scores were drawn from 13 surveys and assessments published between January 2009 and September 2010 by "independent and reputable institutions," according to Transparency International. It defines corruption as the abuse of entrusted power for private gain.

Transparency International is a nongovernmental organization headquartered in Berlin. It acknowledges that corruption, by nature, is often hidden and therefore difficult to quantify, but it says it has found people's perceptions to be a reliable estimate over the long term.